Marine vessels often use “raw” water, for example, untreated sea water or lake water, for engine cooling. An open loop cooling system uses raw water as the sole coolant, drawing raw water into the system through an inlet formed on a drive unit or on the hull, circulating the raw water through the engine coolant passages, and discharging the raw water through the engine exhaust. A second type of system includes a closed loop part that circulates a coolant fluid (typically, a water-propylene glycol mixture) through engine coolant passages and through a water-to-water heat exchanger. A second part of the system draws raw water from outside the hull and directs it through the heat exchanger to remove heat from the coolant fluid. The raw water is then discharged through the engine exhaust system.
Both types of cooling system require occasional draining of the raw water from the cooling system. For example, raw water should be drained from the system when the ambient temperature is expected to fall below freezing to prevent damage to the engine (in the open loop system) or other coolant system components. Raw water is also drained so that the cooling system can be flushed with fresh water to remove salt residue, silt, and other undesirable substances.
Stern drives have engines mounted inside the hull. Draining cooling water from these arrangements includes opening a drain cock, removing a plug, or detaching a hose located at a low point of the cooling circuit and allowing the water to drain into the bilge under the force of gravity. Because it is located at a low point, the drain cock, plug, or hose is often difficult to reach. To solve this problem, U.S. Pat. No. 6,390,870 to Hughes, et al. proposes an open loop cooling system having a manifold located at a low point of the engine cooling system to which the various cooling hoses are connected. The manifold includes a drain tube. An elongated rod is mounted for movement that opens and closes the drain tube, the rod having a plug end that is removably inserted in the drain tube and a handle at an end accessible at a location above the manifold.
To drain the cooling system while the vessel is in the water, that is, when the raw water intake is submerged in the water, it is necessary to prevent siphoning of new raw water into the system as the draining raw water flows from the drain. This may be done by opening a vent in the water line to allow air in the line. Examples of vents in the art include passive vents, for example, float valve controlled vents and manually operated vents.
The invention provides an apparatus for draining a marine engine cooling system, including a raw water passageway having a raw water intake for drawing raw water into the raw water passageway, and including a conduit arranged to have a vertically high point and a vertically low point, a drain valve connected to the raw water passageway at the conduit vertically low point, a vent line connected to the raw water passageway at the conduit vertically high point and, a control handle located remote from the conduit vertically high point and the conduit vertically low point, the control handle being operatively connected to a vent valve connected to the vent line, wherein actuating movement of the control handle selectively opens and closes the vent valve.
According to the invention, the control handle is connected to the drain valve by a cable, and the actuating movement of the control handle that opens and closes the vent valve simultaneously opens and closes the drain valve.
According to an embodiment of the invention, the drain valve includes a hollow, cylindrical body having a drain inlet and a drain outlet, with a spool disposed in the hollow, cylindrical body and connected to the cable, the spool having a first position preventing flow between the drain inlet and the drain outlet and a second position connecting the drain inlet and the drain outlet.
According to another aspect of the invention, the vent valve is integrated in the control handle. The control handle of this embodiment comprises a tubular body having a vent port to which the vent line is connected and having an air relief opening, and comprising a valve member movably disposed in the tubular body having a closed position blocking flow between the vent port and the air relief opening and having an open position allowing flow between the vent port and the air relief opening.
Alternatively, the vent valve is located remote of the control handle and the control handle is connected to the vent valve by a cable.